Variable speed mechanism



Aug. 24, 1954 C. G. UMSTED VARIABLE SPEED MECHANISM 2 Sheets-Sheet 1 Filed Aug. 17, 1946 6. R 5 m, N T WEMM ma 1 Y B i;

C. G. UMSTED VARIABLE SPEED MECHANISM Aug. 24, 1954 2 Sheets-Sheet 2 Filed Aug. 17, 1946 Patented Aug. 24, i954 VARIABLE SPEED MECHANISM Carleton G. Umsted, Northport, N. Y., assignor to The Sperry Corporation,

Delaware a corporation of Application August 17, 1946, Serial No. 691,310

'7 Claims.

This invention relates to a variable speed mechanism and has for its object the provision of I a rugged, accurate, variable speed mechanism operable with a minimum of friction and suitable for assembly in mass production without com plicated gauging operations.

Another object of the invention is the provision of a variable speed mechanism so designed that all parts thereof are readily accessible and adjustable with no tools other than a screw driver. l l

The variable speed mechanism of the present invention is designed primarily for use in gun fire control computers where extreme accuracy is required. At the same time, the device is sufficiently rugged to withstand the effects of nearby gunfire.

The invention contemplates a novel, independ-.

ently supported and substantially frictionless ball carriage having a two-ball motion transmitting arrangement. The ball carriage is supported by three roller bearings of substantially hourglass shape which are symmetrically arranged with respect to the common axis of the motion transmitting balls, in the form of a triangle. The roller bearings are mounted on ball bearings and ride upon two rather widely spaced half round rails. The respective rollers engage points on opposite sides of the rails. This arrangement provides a three-point substantially frictionless support which maintains the ball carriage in the plane in which it travels independently of other parts of the mechanism, and thereby provides a more freely running assembly, operating with less play and greater accuracy than former structures in which the motion transmitting balls are relied upon, at least to some extent, to reduce carriage friction and stabilize the carriage as it is adjusted.

The invention will now be described with the aid of the accompanying drawings, of which:

Fig. 1 is a view in elevation of a variable speed mechanism according to a preferred embodiment of the invention;

Fig. 2 is a vertical section taken through 2--2 of Fig. 1;

Fig. 3 is a view showing the ball carriage and associated parts in elevation; and

Fig. 4 is a horizontal section taken through 4-4 of Fig. 1.

The variable speed mechanism comprises two castings, hinged to each other which serve as a framework for the device. The front casting In according to Fig. 1 is provided with two spaced lugs H and I2 formed thereon which project 2 toward the rear, at the lower part of the casting. The lugs form one part of a hinge and are formed with bearing openings to receive short heavy shafts l3 and I4 of the opposite part of the hinge. These shafts are fixed respectively in lugs l5 and I6 formed on a plate ll secured by screws, such as screw I8, to the under surface of a second or rear casting 20.

Casting I0 supports a novel rotary disc assembly, the disc 24 and the bearings therefor being assembled in a single readily replaceable unit, and provision is made for adjusting the position of the disc with respect to the casting IE! to take care of irregularities in manufacture.

The disc 24 is formed with a coaxially disposed shaft or spindle 25 having a hub 26 formed thereon immediately adjacent the disc, the hub being very large in proportion to the diameter of the spindle so as to provide adequate support for the disc when the balls of the ball carriage, to be described, are positioned near the edge of the disc.

Hub 26 turns in a ball bearing assembly 21 which serves also as a thrust bearing. Spindle 25 turns in a ball bearing assembly 28. A lock washer 29 is disposed on the spindle alongside bearing assembly 28. Both ball bearing assemblies are supported within a removable bushing 3|] which is retained in an opening in casting It by a flange 3| formed at one end of the bushing and a second removable flange 32 secured by screws 33 to the opposite end of the bushing. The opening in bushing 30 in which the bearings are supported is formed eccentrically with respect to the outer surface of the bushing. This eccentric offset is quite small but for clarity it is shown in Fig. 1 considerably exaggerated. This eccentric arrangement permits the bushing to be rotated to shift the center of the disc with respect to the balls of the ball carriage so that the balls will pass accurately through the axis of the disc.

A ball carriage and tracks therefor of novel construction are supported by casting 26, together with a cooperating roller.

Referring to Figs. 1 and 2, the casting or framework 20 is formed with a rear wall 40, a bottom wall 4|, side walls 42 and 43 and a top wall 44. The top and side walls are formed with forwardly projecting members 45 and 46 having fiat surfaces for the purpose of mounting the device on some suitable support.

A round rail 49 having a flat surface on one side is fastened by screws 50 and 5| to a block 52 attached by screws 53 and dowel pins 54 to an enlarged central portion of the top wall 44 in spaced relation with the rear wall 49 of casting 20. A similar but longer rail 56 is attached to a block 59 in the same manner. Block 59 is attached to'a thickened portion 69 of the bottom of the casing by screws BI and dowels 62. The rails are parallel to each other and so mounted as to be parallel to the plane of disc 24 when the latter is inoperating position.

The ball carriage 63- rides between the rails. The ball carriage comprises an approximately flat cast framework 64, the outline of which i541 shown in Fig. 3 in elevation while. verticalsec-i tions and transverse sections thereof'are shown in Figs. 2 and 4, respectively.

A boss 69 formed on the upper.- surface: of; framework -64 has a recess 65 formed therein which partly overlaps rail 49-on.opposite sidesthereof. Bearings 66 and 61, disposed in openings in the boss on opposite sides of the recess, support a roller 68 which rides on rail 49. The central portion .of :the roller. 18 011.13 away form-ingvg sloping flanges which engage ,oppositecnds of ya chord. of,the curved rail. The bearings are-held; in their recesses by removable approximately circular cover plates attached to. the framework: by suitable screws. The cover: plate 01' bear,- ing R56. is shown in Fig. 3.

Bosses l2 and I3, formed-at.opposite'endsof: the lower partofjframework; have-recesses-therein which overlap opposite, sides-of the lower; rail 5.

5.6. Rollers T4: 2.11111 indicated .by\ dottedzlines; in Fig. 3, are mounted in. the recessesinthe re spective bosses, thearrangementbeingthe same, as for the upper. roller 68'.

A rack 76, Figs. 2-and 4, is-secured'to .tha-rear of the carriage. A gearv ll'formed 01113; shaft". litmeshes with the rack,.shaft 78:. being used; to. displace the ball carriage in the usual manner: Shaft iilris. mounted in a removable, ball. bearing: unit 89 fittedinto an opening in the. lowercentral portion of the rear wall' 49.2 of castinglile where the unit is secured in position by airing 8! attached to the casting. byv screws. 82:.

A central opening 8G, disposed to:b.e.-1 brought. into register with the center of disc 24 isformed': in the framework 6.4;, of the .ball carriage.- Mo-v tion communicating ballsBfi-land 3532.116. disposed; in opening 84. The opening is somewhatrlarger; than the ballswhich areheld clear ofrthe. sides: thereof by a novel antifriction roller arrange-- ment which will'now be. described.

A pairof rather thick approximately. triangular plates 89 and 99 are-securedside byssidelbysuitable screws to the front: part, asshownlin Fig. 3, of the casting 64: of the: ballicarriage; while a similar pair of plates-9| and 92-Iare".-se.- cured to the rear thereof. Plates-89- andi99i'have. adjacent edges formed with comp1ementarysemi+ circular recesses therein which, when .the:=plates l are in position, form acircular. opening. which; is in register with the central opening:84 0f7the. framework M. The rear plates .91 and. 92 are shaped in the corresponding manner;

Each plate 8992 has a-pair ofslotszformed therein at right angles to each other and'so'located that each slot of one plate isaligned with" a corresponding slot'of the adjacent plate.

Antifriction rollers 95 and Stiare. mountedetin. the slots of plate 99 which similanrollers; 9:! and 98 are mounted in the. slots of plateflflc. The? bearings for the respective. rollersare ofisetfrom; the central planes of the respective plates in order that'the outer edges ofthe rollers willgbedisposed below the outerisurfaces .of;.the..p lates to protect .the ,rather delicate. shafts of .,the. rollers.

position of. the respective plates 89-432.

4 from injury. With this arrangement, the rollers project beyond the inner surfaces of their supporting plates but recesses are cut in the central part of the framework 64 into which the projecting portions of the rollers extend whereby the rollers freely revolve in their bearings clear of the framework.

The parts just described'areso:located that ballsand 86 are each=supportedby-a set of four rollers. While all of the parts herein described are intended to be of precision manufacture, some. adjustment may be made to compensate for wear, irregularities in manufacture andgfor".easyv repair; by slight adjustments in the It is thought that-this-will be understood from inspection .of the, drawings.

The balls of the ball carriage cooperate with a roller in the known manner. Shaft 99, which has a roller [99 formed thereon, turns in bearings I01 mounted in suitable; openingsiin the: side walls dr and 43;:ofcasting 20: The .-openings-arelargeenoughlto permitthe shaft and drum to: pass therethrough' when eitherbearing, is re-. moved. Rings [02,;secured-dn positionbysuitable screws, are provided"forretaining-thebearings; I91 in their; openings.

Theballs B5 and- 86 areyyieldingly; pressed.- betweendiscmtandzroller lflt by av spring I05:- enclosed-qwithin a; sleeve I06 having aansexternal. flange I01 formed at one end. The sleeve'extends through: an 1 opening in ,the upper.- part of casting lllwhere its flange I 01 .restsnon'a shoulder formedabout theopening: An internallythread ed hollow stud I99, secured;to casting 20,: Pro-- jects .into sleeve;v [065 clearof j the,- sides thereof: The spring is variably compressed betweenan. internal flange: H0 formed;on,thezsleevesanda cap. HI bymeans of a screw H2 whichextends. through an opening in; the cap and; is threaded into the threaded portionof stud I09.

Since many changes could-be made in the above construction and many-apparently; widelydifferent embodiments-of this-invention could, bemade without departing from1thescope-thereof, it isintendedthatall matter contained in the above description or showninthe-accompanying draw. ingstshall be. interpreted as illustrative; and not in a limiting sense:. 1

What is claimedis:

1. A variable speed mechanismcomprising-- a framework having an-opening; formed @therein', a l bushing rotatahly disposed inzthegopening having; a boreslightly off center, a disc a shaft therefor;

.. bearing means'for the shaft effective;tozsupport;

the disc against-thrust disposedin-the; bore-, .a: movable ball carriage, and .roller disposed in the framework cooperating with the disc; and-means for seeming the-hushing against; rotation in :the opening, the. arrangement being 1 such that the bushing may be turned torp csiticnqtheqcenter of: the? disc. lwithqreference to' the path of the ball carriage;

2. A variable speed mechanism. comprising a; framewcrkghaving an opening formed. therein; a bushing rotatably disposed in the opening' h'aveing a flange forme'dat one-endandfabore slightly off center withrespect :tothe outera-surfacei of the: bushing, a disc; ashaft fixed-to the disc, bearing means for the shaft disposed in the borereffective to. support the discagainstthrust, ag movable ball carriage. and roller disposed in theframework. cooperating with the disc, a..retaining flange r emovably, attached. tothe. opposite. end. of the bushing cooperating with the. first; mentioned;

flange for securing the bushing in position, the arrangement being such that the disc and the bearing means for the shaft may be installed as a unit in the framework and the axis of the disc may be thereafter adjusted with reference to the path of the ball carriage by rotating the bushing in the opening.

3. A variable speed mechanism comprising a framework having an opening formed therein, a bushing disposed for rotation in the opening having a bore formed slightly off center, a disc, a shaft therefore having a relatively large hub formed thereon adjacent to the disc, an antifriction bearing for the hub disposed in the bore of the bushing for supporting the disc against thrust, particularly thrust exerted thereon at points remote from the center of the disc, a second antifriction bearing for the shaft disposed in the bore, a ball carriage and a cooperating roller disposed in the framework, and means for detachably securing the bushing in the opening, the bushing being adapted to be rotated to position the center of the disc with reference to the path of the ball carriage.

4. A variable speed mechanism comprising a two-part framework, hinge means connecting the parts, a roller and a cooperating ball carriage disposed in one part of the framework, bearing means disposed in the other part of the framework, a disc supported for rotation in the bearing means cooperating with the ball carriage, eccentric means supporting the bearing means for adjusting the position of the center of the disc with reference to the ball carriage, and spring means jointly supported by both parts of the framework for pressing the parts together.

5. A variable speed mechanism comprising a two-part framework, hinge means connecting the parts of the framework, a roller and a cooperating ball carriage disposed in one part of the framework, bearing means disposed in the other part of the framework, a disc supported for rotation in the bearing means cooperating with the ball carriage, and eccentrically formed means for supporting the bearing means for adjusting the position of the disc with reference to the ball carriage.

6. A variable speed mechanism comprising a two-part framework, hinge means connecting the parts of the framework, a roller and a cooperating ball carriage disposed in one part of the framework, a bushing having an eccentrically formed bore disposed in the other part of the framework, bearing means disposed in the bore of the bushing, a disc cooperating with the ball carriage disposed in the bearing means, and means for movably securing the bushing in the framework to adjust the position of the disc with reference to the ball carriage.

7. A variable speed mechanism comprising a two-part framework, a hinge connecting the parts of the framework, a roller and a cooperating ball carriage disposed in one part of the framework, a rotary disc assembly cooperating with the ball carriage disposed in the other part of the framework comprising a spindle for the disc having a relatively large hub formed thereon adjacent the disc, a bushing, ball bearing means in the bushing for the hub adapted to support the disc, particularly the outer portions thereof, against thrust, other ball bearing means in the bushing for the spindle, means for detachably securing the disc assembly as a unit in said other part of the framework, and means responsive to the rotation of the bushing with respect to the frame for adjusting the position of the center of the disc with respect to the ball carriage.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,398,417 Chicken et a1 Nov. 29, 1921 2,139,234 Johnson Dec. 6, 1938 2,357,035 Treese et a1 Aug. 29, 1944 

